1. Field of the Invention
The present invention relates to a support arm, and more particularly to a support arm with a multiple degree of freedom locking device.
2. Description of the Prior Art
Referring to FIG. 1, a conventional support arm for a gravity balance mechanism comprises: a lower rack 11, an upper connecting rod 12 and a lower connecting rod 13 each have one end connected to the lower rack 11, a spring 14 disposed between the upper and lower connecting rods 12, 13, and an upper rack 15 which is provided for mounting of a tool (not shown) is connected to another end of the upper and lower connecting rods 12, 13. With the multi-link device and the spring 14, the support arm 10 is able to support and fix the tool. Furthermore, with the spring 14 disposed between the upper and lower connecting rods 12, 13, the support force provided by the support arm 10 can change along with the change of rotation angle to support the weight of the tool, and the tool can be well positioned during the adjustment process or after adjustment, without the possibility of moving under the influence of gravity.
However, the adjustment of the tool usually involves multiple degrees of freedom, and the support arm 10 itself does not allow locking and adjustment of different degrees of freedom.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.